1. Mac Operating System List
2. Upgrades For Mac Computer Operating System
3. New Operating System For Imac
4. What Is The Current Operating System For Mac Computers

Apple offers some great computer hardware options, with gorgeous industrial design on Macbooks, optional 5K screens on iMacs, and the new, massively powerful Mac Pro (starting at $5,999). The mac operating system is incredibly easy to use and 9 out of 10 times hardware will be plug and play. I’ve written a indepth review to of low latency audio interfaces that are compatibile with the apple mac operating system. Linux Operating System. Linux was initially released in 1991 and is a free opensource operating system.

The 'missing operating system' or 'operating system not found' error message usually appears on a black window when you start Windows computers. It would prevent you from booting Windows. This error is very common for Dell, Acer, Lenovo, HP, and Sony desktops and laptops. You can read on to get error details or skip directly to solutions.

Causes of Missing Operating System/Operating System Not Found

Generally, when something goes wrong with the BIOS configuration, hard drive health, or the Master Boot Record (MBR), you can't boot the Windows and will see the mentioned two error messages. To be specific, the causes that lead to Operating System Not Found are as follows.

• The basic input/output system (BIOS) does not detect the hard disk
• The hard disk drive is damaged
• Improper/incorrect BIOS settings
• Windows Master Boot Record (MBR) is corrupt/damaged
• An incompatible partition is set as active

Note: If the BIOS fails to detect the operating system, you will receive one of the following error messages, which tells the same problem on different operating system versions.

Error message 1: Missing Operating System

Error message 2: Operating system not found

7 Solutions to Fix Operating System Not Found or Missing

After knowing the causes for an operating system not found or missing in Windows, now it's time to apply effective solutions to restore the missing operating system.

Solution 1. Check if the hard drive is detected by BIOS

Step 1: Press and hold 'F12/F10' while pressing the 'Power' button to turn on the PC.

Step 2: Release F12/F10 when the BIOS Setup Utility is displayed.

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Step 3: Try to find IDE Primary Master, IDE Primary Slave, IDE Secondary Master, and check whether they can be detected or not.

If no disk is shown or displayed as None/Not Detected, it means that the BIOS doesn't detect the drive and you may select None to Auto. This may solve OS not found error.

If the system disk information is displayed, it means that BIOS can detect the hard drive and you need exit BIOS.

Solution 2. Test hard drive problems

Step 1: Press and hold 'F10' and press the 'Power' button to turn on the PC > Release F10 after the PC screen display you with a test.

Step 2: Use the right arrow to select the 'Tools' menu in the BIOS Setup Utility.

Step 3: Then select 'Hard Drive Self Test' > Press 'Enter' to start the test.

After the test, you'll get two results:

#1. All tests passed

the hard drive is not damaged. You may jump to Solution 3 to reset BIOS to the default state.

#2. The test failed

You should contact your hard disk or computer manufacturer for a replacement as long as these devices are under warranty.

Solution 3. Set BIOS to default settings

Improper settings or incorrect BIOS settings may also cause the issue 'operating system not found' in your PC. You can try to set BIOS to default settings to solve the problem.

Step 1: Restart PC and enter BIOS.

Step 2: Find BIOS and enable the default setup option, including Load Optimal Defaults, Get Default Values, Load Optimized Defaults, Load Setup Defaults, and so on.

Step 3: Press 'F10' to save changes and quit from BIOS.

If this method doesn't work, the MBR disk could be damaged and you may jump to Solution 4 to find the MBR disk repair method.

Solution 4. Repair MBR with the installation CD/DVD

Both wrong operation and virus infection can damage MBR, which locates in the first sector - usually sector 0 of the hard disk. Thus, Windows will not boot. You can try to repair MBR using the Windows installation disk in Command Prompt.

Insert Windows Operating System Disc to the optical (CD/DVD) drive

Step 1: Press the 'Power' button to turn on the PC > Hit 'Enter' when Boot from CD prompt.

Step 2: Press 'R' key in Windows Setup Menu to start the Recovery Console.

Step 3: Type: FIXMBR at the C:> prompt and hit 'Enter'.

Step 4: Press 'Y' key > hit 'Enter' when asked if you want to write a new MBR.

Step 5: Restart PC by pressing the 'Power' button when the MBR completes the writing process.

Solution 5. Rebuild MBR without Windows installation CD/DVD

If you prefer an easier and safer way to rebuild or repair the MBR disk, you may apply third-party partition magic software - EaseUS Partition Master to perform an automatic repair.

Boot your Windows from the WinPE environment you created and start to repair MBR with a few clicks.

Step 1.Create a WinPE bootable disk.

• Download and launch EaseUS Partition Master on a new PC which runs the same system as yours.
• Click 'WinPE Creator' on the toolbar. And select to create the bootable disk on a USB drive. If your computer has a CD/DVD drive, you can also create the bootable disk to CD/DVD.
• Click 'Proceed' to finish the process.

Step 2.Rebuild MBR.

• Connect the bootable USB or CD/DVD to your PC.
• Press 'Del' when you are restarting the computer. Boot your computer from 'Removable Devices' or 'CD-ROM Drive'. And then EaseUS Partition Master will run automatically.
• Right-click the disk whose MBR is damaged. Choose 'Rebuild MBR' to continue.

• Select the type of MBR with the current operating system. Then, click 'OK'.

• Click the 'Execute 1 Operation' button at the top-left corner and click 'Apply' to build the MBR. After that, your computer can boot normally again.

Solution 6. Repair MBR for HP

Solution 4~5 to corrupted MBR repair is applicable to various computer/laptop brands. On top of that, some brands provide customers with inbuilt tools to deal with MBR issues. For example, the Windows Operating System Disc (OSD) provided with HP notebook PC can be used to repair the Master Boot Record.

Follow all steps at https://support.hp.com/us-en/document/c00476274

Solution 7. Set the correct partition active

When Windows is running under Legacy BIOS + MBR mode, the boot partition/system partition should be set as active so that MBR can pass boot right to boot manager and find Windows. If the system partition or boot partition is not set to active, you may encounter the operating system not found issue.

In the same partition tool, create the EaseUS Partition Master bootable USB first, and follow the steps to set the boot partition active:

Step 1. Download and launch EaseUS partition manager software.

Step 2. On the disk map, right-click the desired partition and choose 'Set Active'. The software will automatically execute the operation and create an active partition for you.

Upgrades For Mac Computer Operating System

Conclusion

All effective solutions to the 'Missing Operating System' or 'Operating system not found' error are carefully presented on this page. You may try any one of the methods to resolve the issue and get a healthy Windows system back and continue using your computer again.

How to get updates for macOS Mojave or later

If you've upgraded to macOS Mojave or later, follow these steps to keep it up to date:

1. Choose System Preferences from the Apple menu , then click Software Update to check for updates.
   
2. If any updates are available, click the Update Now button to install them. Or click ”More info” to see details about each update and select specific updates to install.
   
3. When Software Update says that your Mac is up to date, the installed version of macOS and all of its apps are also up to date. That includes Safari, iTunes, Books, Messages, Mail, Calendar, Photos, and FaceTime.

To find updates for iMovie, Garageband, Pages, Numbers, Keynote, and other apps that were downloaded separately from the App Store, open the App Store on your Mac, then click the Updates tab.

To automatically install macOS updates in the future, including apps that were downloaded separately from the App Store, select ”Automatically keep my Mac up to date.” Your Mac will notify you when updates require it to restart, so you can always choose to install those later.

How to get updates for earlier macOS versions

If you're using an earlier macOS, such as macOS High Sierra, Sierra, El Capitan, or earlier,* follow these steps to keep it up to date:

1. Open the App Store app on your Mac.
2. Click Updates in the App Store toolbar.
3. Use the Update buttons to download and install any updates listed.
4. When the App Store shows no more updates, the installed version of macOS and all of its apps are up to date. That includes Safari, iTunes, iBooks, Messages, Mail, Calendar, Photos, and FaceTime. Later versions may be available by upgrading your macOS.

To automatically download updates in the future, choose Apple menu  > System Preferences, click App Store, then select ”Download newly available updates in the background.” Your Mac will notify you when updates are ready to install.

* If you're using OS X Lion or Snow Leopard, get OS X updates by choosing Apple menu  > Software Update.

New Operating System For Imac

How to get updates for iOS

Learn how to update your iPhone, iPad, or iPod touch to the latest version of iOS.

Learn more

What Is The Current Operating System For Mac Computers

• Learn how to upgrade to the latest version of macOS.
• Find out which macOS your Mac is using.
• You can redownload apps that you previously downloaded from the App Store.
• Your Mac doesn't automatically download large updates when it's using a Personal Hotspot.